Telephone



T. A. WATSON.

Patented Aug. 2,18 81.

V V V/ I//// /////A UNITED STATES PATENT OFFICE.

THOMAS A. WATSON, OFBOSTON, MASSACHUSETTS.

TELEPHONE.

SPECIFICATION forming part of Letters Patent No. 45,105, dated August 2,1881,

' Application filed April 25, 1878.

To all whom it may concern:

Be it known that I, THOMAS A. WATSON, of Boston, Massachusetts, haveinvented a' new and useful Improvement in Telephones, which improvementis fully set forth in the following specification.

This invention relates to telephones or telephonic transmitters in whichundulatory currents are produced in a battery-circuit by the variationsof pressure between electrodes, which variationsiu pressure createcorrespondin g variations in the resistance of the circuit, andconsequently in the tension of the current on said circuit. Thesevariations in pressure are caused by the vibration of a diaphragm orelastic plate. One of the electrodes is usually carbon.

The present invention has for its object to secure increased efliciencyin the conversion of sound-waves into electric undulations; and to thisend it consists in the construction and combination of parts ashereinafter more fully set forth, whereby the diaphragm is allowed tovibrate freely under the action of the soundwaves, and a more perfectcontact between the electrodes and a better transmission of pressure tothem from. the diaphragm are at the same time secured.

In the accompanying drawings, which form a part of this specification,Figure 1 is a sectional view of a telephone embodying the invention, andFig. 2 a diagram illustrating the manner in which such an instrument isor may be connected in circuit for use with a receivingtelephone.

In Fig. 1, A is a mouthpiece for conveying the sound-waves, to thevibratory plate or diaphragm B, which is formed of a thin sheet of metalin the usual way. diaphragm is rigidly secured a metallic piece orelectrode, E, which makes contact with a carbon disk or electrode, 0.This metallic piece has a small surface in contact with the diaphragm,so as to interfere as little as may be with the vibration of the latter,while a larger surface is preferably in contact with the point wereused, thus producing better results To the center of this' bydiminishing the resistance offered to the passage of the electriccurrent from one electrode tothe other, and at the same time diminishingthe liability of the two electrodes to break orbecome separated, so asto interrupt the current.

As shown, the carbon button or disk is hollowed to receive the rigidmetallic piece or electrode.

At the back of the instrument is a support, F, having a threaded openingfor the set-screw D. This screw is fitted to or bears at the inner endagainst the carbon button or electrode and serves to regulate thepressure of the same upon the metallic electrode or rigid piece, whichis interposed between it and the diaphragm B. It will be seen,therefore, that words or other sounds uttered into the mouth-piece Awill communicate vibration to the diaphragm B, and will vary thepressure between the electrodes E O, and will increase or diminish thecurrent flowing over a battery-circuit including the electrodes.

The circuit is completed by connecting the opposite poles of a batteryby suitable conductors with the binding-posts G H. The post G is carriedby the support F, which, as shown, is a rigid support of metal. The postH is electrically connected with the diaphragm, and the circuit passesfrom one post to the other through the diaphragm, metallicconnectingpieoe E, or metallic electrode, carbon electrode 0, screw D,and support F. V

In Fig. 2 the telephone-receiver A is shown included in the secondarycircuit b of an induction-coil, B, and the transmitter O and battery Dincluded in the primary circuit a of the same. This figure is onlyintended to illustrate the manner of connecting the instruments incircuit,the particular construction of the transmitter constituting thepresent invention not being illustrated.

The connection of a carbon-telephone with a receiver and induction-coil,as shown, constitutes no part of thepresent invention.

Having thus fully described the said invention and the manner ofcarrying the same into effect, what I claim, and desire to secure byLetters Patent, is

1. The combination, with a telephone diaphragm or vibratory plate, of anelectrode attached at the center of said plate or diaphragm, and havinga small area in contact therewith, so as to interfere as little aspossible with the vibration of the plate or diaphragm, substantially asdescribed.

2. A telephone-transmitter comprising a vibratory diaphragm, anelectrode connected with the diaphragm so as to partake of itsvibration, and having a small area in contact therewith, and a secondelectrode in electrical contact with the vibratory electrode,substantially as described.

3. The combination of a diaphragm, a carbon button or disk forming anelectrode, an electrode connected with the diaphragm so as to partake ofits vibrations, and interposed nesses.

T. A. WATSON. Witnesses:

R. W. DEVONSHIRE, A. E. COLE.

